As far as I can see from Chambers and the Oxford Dictionary Online, people may be “hung” or “hanged” but the latter is rather more common.

The Oxford one goes on to explain:

The reason for this distinction is a complex historical one: hanged, the earlier form, was superseded by hung sometime after the 16th century; it is likely that the retention of hanged for the execution sense may have to do with the tendency of archaic forms to remain in the legal language of the courts